Imaging- vs. Scalp-Targeted Accelerated TMS for Depression: The Number Needed to Scan Trial

Major depressive disorder (MDD) remains a leading cause of global disease burden and disability. In addition to increasing the risk of death by suicide, MDD also shows a graded positive association with all-cause mortality. Antidepressants are the most frequently prescribed medication class in psychiatry and, once started, are often continued for many year. However, antidepressants have a small-to-moderate effect size that might be inflated by publication bias. Most people with MDD do not achieve remission with their first antidepressant, and the probability of getting well and staying well diminishes with each sequential trial. By the fourth trial, remission rates approach single digits. Depression that does not improve with one or more antidepressant classes is often considered "difficult-to-treat" or "treatment-resistant" depression (TRD). Taken together, these data highlight the need for better and faster treatments for TRD.

TMS for TRD is safe, well-tolerated, and often covered by insurance. Unlike esketamine and ECT, TMS does not require supervised transportation after treatment. However, TMS is: 1) time intensive, requiring daily weekday treatments for 6-8 weeks; 2) imprecisely targeted based on scalp measurements, which means that each person is stimulated at a slightly different site; and 3) ineffective approximately half the time, with response and remission rates around 50% and 33%, respectively. A new form of accelerated TMS (aTMS) by Cole et. al was designed to address these limitations. In the open-label trial (n=21), the Cole et a. protocol significantly reduced Montgomery-Åsberg Depression Rating Scale (MADRS) in a single day and resulted in a 79.5% reduction one month after treatment. Remission rates were 86% and 57% one week and one month after open-label aTMS, respectively. From this perspective, this specific aTMS protocol works better and faster than conventional TMS and even rivals ECT. The only double-blind randomized controlled trial of this Cole et al. protocol was discontinued after an interim analysis (n=29) revealed a large effect size (Cohen's d>0.8) for active vs. sham (52.5% vs. 11.1% MADRS reduction, respectively). In this trial, remission rates were 57% and 46% one week and month after active aTMS, respectively. There are also emerging data on retreatment and durability. In a recent open-label extension study (n=27), 91% of people who achieved remission with an index course of this specific aTMS protocol (n=22) also achieved remission with aTMS retreatment 6 months later.

In July 2023, investigators launched the "AINT Trial" (NCT05680727). Our goal was to calculate an effect size to power a confirmatory trial. Investigators matched Cole et al. on schedule, dose, intensity, and precision. Investigators also matched Cole et al. inclusion/exclusion criteria (based on published trials and feedback from Stanford colleagues) and its primary outcome measure (i.e., MADRS reduction (% change) one month after aTMS). The goal was to isolate the variable of targeting. Based on our results (in preparation), a sample size of 40 per group will provide ~95% power to detect a between-group difference. Therefore, this study will be a fully powered, double-blind, confirmatory efficacy trial (n=80) for imaging- vs. scalp-targeted aTMS for TRD.